Key to species of Penicillicaris gen. nov.

The swimming leg armature is incompletely known for all species (Table 1). Willey (1935: Fig. 123) noted that in Pe. penicillata sp. nov. the distal exopodal segment of P3–P4 has three inner setae, the distal one of which is “… an excessively fine hair curving outwards…”. It is conceivable that this element has been overlooked in earlier descriptions and thus caution is required when using this key (see couplet 3). Any identification made must be checked against the original description(s).

1. Antennule ♀ 9-segmented; P1 exp-3 with three penicillate spines and one long non-geniculate seta; caudal ramus setae IV–V not modified in ♀ .................................................................... P. maldivensis sp. nov.

– Antennule ♀ 8-segmented; P1 exp-3 with two penicillate spines, one geniculate seta and one shorter non-geniculate seta; caudal ramus setae IV–V with swollen bases in ♀ .................................................................2.

2. P2–P3 endopods ♀ with enp-2 and enp-3 more often very imperfectly separated, without mobile articulation between them (when distinctly 3-segmented no spur at inner distal corner); P4 endopod ♂ with armature pattern [1.1.021] (both inner setae of ♀ not expressed in ♂).................................................................. P. penicillata sp. nov.

– These characters not combined..........................................................................3.

3. P3 exp-3 with seven elements; P5 exopod ♀ about three times longer than maximum width, inner and outer margins mostly parallel; P5 endopodal lobe ♀ reaching to about one third of exopodal length......................... P. sewelli sp. nov.

– P3 exp-3 with eight elements; P5 exopod ♀ about 2.15 times longer than maximum width, inner and outer margins gradually converging towards apex; P5 endopodal lobe ♀ reaching to about one fifth of exopodal length.............................................................................................. P. pectinimana (Car, 1884) comb. nov.